Method and apparatus for reinforcing cup-type grinding wheels

ABSTRACT

The disclosure illustrates the reinforcement of a cup-type grinding wheel which has a peripheral surface tapering from a grinding face. A pair of wheels are positioned face to face while a tape comprising a plurality of strands of filamentary material is wound around the grinding wheels with a portion of each turn on one cup and the remaining portion on the adjacent cup. The wound tape is saturated with a curable resin and the wheels are urged apart by a spring to maintain the tape in tension. After the resin is cured the tape that extends between the junction of the grinding faces for the wheels is cut off to produce two reinforced cup-type grinding wheels.

United States Patent [191 Peterson Apr. 16, 1974 [75] Inventor: GeorgeN. Peterson, Grofton, Mass.

[73] Assignee: Dresser Industries, Inc., Dallas, Tex. [22] Filed: Dec.26, 1972 [21] Appl. No.: 318,445

Related US. Application Data [62] Division of Ser. No. 149,192, June 2,1971,

abandoned.

[56] References Cited UNlTED STATES PATENTS 2,077,771 4/1937 Rae 156/4253,112,234 11/1963 Krupp 156/446' 3,366,522 l/1968 Underwood 156/1613,414,449 12/1968 Beach 156/173 Primary ExaminerDaniel J. FritschAssistant Examiner-Neal Kalishman [5 7] ABSTRACT The disclosureillustrates the reinforcement of a cuptype grinding wheel which has aperipheral surface tapering from a grinding face. A pair of wheels arepositioned face to face while a tape comprising a plurality of strandsof filamentary material is wound around the grinding wheels with aportion of each turn on one cup and the remaining portion on theadjacent cup. The wound tape is saturated with a curable resin and thewheels are urged apart by a spring to maintain the tape in tension.After the resin is cured the tape that extends between the junction ofthe grinding faces for the wheels is cut off to produce two reinforcedcuptype grinding wheels.

10 Claims, 3 Drawing Figures MOTOR METHODAND APPARATUS FOR REINFORCINGCUP-TYPE GRINDING WHEELS This is a continuation, division, ofapplication Ser. No. 149,192 filed June 2, 1971 now abandoned.

The present invention relates to cup-type grinding wheels and moreparticularly to a method and apparatus for reinforcing this type ofwheel.

Inreceht years there has been a tendency toward the operation of thecup-type grinding wheels at ever increasing R.P.M.s to improve theircutting efficiency. The increased operating speeds in some cases are sogreat that the grinding material has insufficient internal strength toresist the centrifugal forces which tend to make it fly apart.

To solve this problem it has been proposed to reinforce the periphery ofthis type of grinding wheel. One such method of reinforcement is to winda number of turns of a continuous strand of filamentary fiberglassmaterial around the peripheral surface of the grinding wheel and it issaturated with a curable resin to form a reinforcing band for theperiphery of the wheel.

It has been found that with this approach it is difficult to maintain auniforin tension in the strands of fiberglass through each and everyturn. This causes some turns to carry more tensile stress than others,thereby lowering the effectiveness of the band in resisting thecentrifugal force acting on the wheel.

Therefore it is an object of the present invention to uniformly andeffectively reinforce the periphery of a cup-type grinding wheel.

In one aspect of the invention the above ends are achieved by a methodwhich comprises the steps of positioning the grinding faces of a pair ofcup-type grinding wheels face to face. A number of turns of at least onestrand of filamentary material is wound around the peripheral surfacesof the wheels and saturated with a curable resin, said strand beingwound in a direction generally nonparallel to the plane of the grindingfaces so that a portion of each turn is on one wheel and the remainingportion on the other wheel. The wound strands are urged apart with asubstantial force while the resin cures to maintain the strands intension.

In another aspect of the invention the above ends are achieved byapparatus which comprises an arbor over which a pair of grinding wheelsare telescoped so that their grinding faces oppose one another. Thewheels areyieldably urged away from one another with a substantial forceand an adjustable limiting means maintains the wheels in a firstposition while the strands of filamentary material are wound aroundthem. The adjustable displacement limiting means is then released topermit the yieldable urging means to displace the wheels away from oneanother so'that the turns of the strand are held in tension.

The above and other related objects and features of the presentinvention will be apparent from a reading of the description of thedisclosure shown in the accompanying drawing and the novelty thereofpointed out in the appended claims.

In the drawing:

FIG. 1 is a diagrammatic view of apparatus used to reinforce theperiphery of a pair of cup-type grinding wheels; and

FIGS. 2 and 3 are views of the cups of FIG. 1 shown in successive stagesin practicing the method of the present invention.

Referring to FIG. 1 there is shown a pair of cup-type grinding wheels 10and 12 which have grinding faces 20 and 22, respectively, and annularperipheral surfaces 11 and 13, repectively, tapering from the grindingfaces. Grinding wheels 10 and 12 have internal openings l4 and 16,respectively, telescoped over an arbor 18 so that their grinding faces20 and 22 are positioned in opposition to one another and spaced apartby a spacing disc 24. Grinding wheel 12 abuts a flange 26 on arbor 18. Aspring 28 acting on interior recesses 30 and 32 of grinding wheels 10and 12 urge them away from one another with a substantial force. Anadjustable limiting means comprises a nut 34 threaded onto arbor 18 tohold the grinding wheels in position against the force of spring 28.

Arbor 18 is connected to and driven by an output shaft 36 of a gear box38. Gear box 38 has an additional output shaft 40 and an input shaft 42which receives a driving input from a shaft 44 of a suitable motor 46.Shaft 40 connects through a right angle gear box 48 to a drive shaft 50which drives a cam 52 via another right angle gear box 54. Cam 52 has afollower 56 attached to an arm 60 connected at right angles to anelement 62 which is displaced in a suitable slot 64 in a directionparallel to the axis of arbor 18. Spring 58 urges element 62 to the leftso that follower 56 is biased against cam 52.

Element 62 has a suitable guide 68 secured to it which forms a guide fora strand 70 of filamentary material, the strand 70 being stored on asuitable drum 72. It has been found that the material used to wind thegrinding wheels may take a number of forms, for example, continuousfilament fiberglass strands comprised of filamentary fiberglassmaterial, fiberglass roving or yarn. For convenience in winding thedrums the strands may be formed in a tape to allow the application of agreat number of strands for a given rotation of arbor 18. All thesetypes of materials may be secured from any number of suppliers known tothose skilled in the art.

The strand 70 is reeled onto the peripheral tapering surfaces 11 and 13of grinding wheels 10 and 12 as described below.

Motor 46 drives arbor 18 to rotate wheels 10 and 12 thus causing strand70 to be unreeled from drum 72 and onto the peripheral tapering surfacesof the wheels. A suitable friction brake 74 retards the rotation of drum72 so that the strand 70 is wound with an initial tension. The strand 70is saturated with a curable resin either before the strand is wound onthe grinding wheels or after, depending upon manufacturing convenience.

The resin is of the type that has a relatively long curing time, asdescribed below. Resins that cure at elevated temperatures have beenfound particularly useful for this operation. An example of this type ofcurable resin is an Epotuf Epoxy Resin mixed with a Versamid No. curingagent in a 70 30 percent by weight mixture. The Epotuf Epoxy Resin ismanufactured by Reichhold Chemicals, Inc., Azusa, Ca., and the Versamidcuring agent by General Mills chemical division. This particular mixturecures at F. for 8 hours. It should be apparent to those skilled in theart that a wide variety of curable resins may be selected to giveacceptable results for this method.

As motor 46 drives arbor 18 through gear box 38, cam 52 is rotatedthereby displacing guide 68 back and forth in a direction parallel tothe axis of arbor 18. The gear ratios of the gear boxes are selected sothat guide 68 will be in line with one of the grinding wheels forgreater than 90 rotation of arbor 18 at which point the guide crossesover to the adjacent cup. This causes the strand to be wound in a numberof turns on the cups with a portion of each 360 turn of arbor 18 beingon one wheel and the remaining portion of the turn on the adjacentwheel. With the arrangement shown each wheel has the strand 70 wound onits peripheral surface for greater than 90 of its rotation at whichpoint the strand passes to the adjacent cup. The adjacent cup has thestrand wound on its surface for the same degree of rotation. The netresult of this is that the point at which the strand 70 crosses from onewheel to the next is at a different peripheral position as succeedingturns are applied to the wheels. The degree to which the tape is woundon each drum may vary from between 90 to 360. It has been found that awinding of approximately 240 gives acceptable results.

When the wheels are wound with sufficient strand the strand 70 issevered and suitable tucked into the wound strand After the wheels arewound with the saturated resin the nut 34 is loosened, as shown in FIG.2, so that the spring 28 is free to displace the grinding wheels and 12away from one another with substantial force. The wound strand restrainsthe outward displacement of the grinding wheels and 'as a result isplaced under a substantial peripheral tension. lt has been found that aspring force of approximately 1,100 lbs gives acceptable results.However, other force levels may be selected for particular applications.The long curing time of the resin enables the tension in the succeedingturns of strand to be equalized so that each turn uniformly is stressedin response to centrifugal forces on the wheel.

When the resin is cured the nut 34 is advanced to a position where itabuts the face of grinding wheel 10 in the expanded position and then acut-off wheel 76 is applied to sever the tape 70 at the point at whichit crosses from one grinding wheel to the next. The wheels 10 and 12 arethen removed from the arbor 18 for use.

The reinforcement that results with the invention described above ishighly effective in resisting centrifugal stresses placed on thegrinding wheels 10 and 12. Since the wheels are tensioned during curingto maintain a uniform stress, each and every strand contributesuniformly to strengthening the wheel. While the strands are notcontinuous around the periphery of the individual wheel, they are bondedto one another around a sufficient portion of the periphery to maintaina highly effective reinforcement. Furthermore, as the grinding faces 20and 22 are worn away, the reinforcing strands are cleanly cut away attheir ends instead of being frayed, as is the case with prior artreinforcing where continuous strands are wound parallel to the grindingface.

While a preferred improvement of the present invention has beendescribed, it should be apparent to those skilled in the art that theinvention may be practiced in different manners without departing fromits spirit and scope.

Having thus described the invention what is claimed as novel and desiredto be secured by Letters Patent of the United States is:

l. A method reinforcing cup-type grinding wheels having annularperipheral surfaces tapering from grinding faces, said method comprisingthe steps of:

positioning the grinding faces of a pair of wheels face to face;

winding a number of turns of at least one strand of filamentary materialaround the peripheral surfaces of said wheels and saturating the strandwith a curable resin, said strand being wound in a direction nonparallelto the grinding faces so that a portion of each turn is on one wheel andthe remaining portion is on the other wheel; and

urging said wheels apart with a substantial force while the resin curesthereby maintaining said strands in tension.

2. A method as in claim 1 wherein said strand is wound on said grindingwheels with an initial tension so that urging the wheels apartsubstantially increases the tension of said wound strand.

3. A method as in claim 2 wherein a plurality of strands of filamentarymaterial comprising a tape are wound around the peripheral surfaces ofsaid grinding wheels.

4. A method as in claim 1 further comprising the step of severing thestrands of filamentary material at the junction between said wheelsafter said resin is cured whereby each wheel is reinforced by aplurality of strands of filamentary material each wrapped aroundportions of the periphery of said wheel.

5.. A method as in claim 1 wherein the strand is saturated with anadhesive incorporating a resin that cures at an elevated temperaturewhereby sufficient curing time is permitted for the tension in the turnsof the wound strand to be equalized and thereby permitting uniformtransfer of the loads between the strand and the peripheral surfaces ofsaid grinding wheels.

6. A method as in claim 1 wherein the strands are wound so that over andless than 360 of the peripheral surface of each wheel is traversed bythe strand before crossing over to the other wheel whereby the strandcrosses from one wheel to the other at successive positions around theperiphery of the grinding faces.

7. A method as in claim 6 wherein said strands are wound overapproximately 240 of the peripheral surface of each wheel.

8. Apparatus for reinforcing cup-type grinding wheels having annularperipheral surfaces tapering from grinding faces, said apparatuscomprising:

an arbor for mounting a pair of wheels with their grinding facesopposing one another;

means for yieldably urging said wheels away from one another with asubstantial force;

means for adjustably limiting the displacement of said wheels away fromone another, said adjustable displacement limiting means positioningsaid wheels in a first position wherein the peripheral surfaces of saidwheels are wound with a number of turns of at least one strand offilamentary material, a portion of each turn being on one wheel and theremaining portion being on the other wheel, and said adjustabledisplacement limiting means being released to permit the yieldableurging means to displace said wheels away from one another whereby theturns of the wound strand are held in tension.

9. Apparatus as in claim 8 further comprising:

the arbor.

10. Apparatus as in claim 9 wherein said feed means feeds the strandonto over and less than 360 of the peripheral surface of each grindingwheel before feeding the strand onto the adjacent wheel.

1. A method reinforcing cup-type grinding wheels having annularperipheral surfaces tapering from grinding faces, said method comprisingthe steps of: positioning the grinding faces of a pair of wheels face toface; winding a number of turns of at least one strand of filamentarymaterial around the peripheral surfaces of said wheels and saturatingthe strand with a curable resin, said strand being wound in a directionnonparallel to the grinding faces so that a portion of each turn is onone wheel and the remaining portion is on the other wheel; and urgingsaid wheels apart with a substantIal force while the resin cures therebymaintaining said strands in tension.
 2. A method as in claim 1 whereinsaid strand is wound on said grinding wheels with an initial tension sothat urging the wheels apart substantially increases the tension of saidwound strand.
 3. A method as in claim 2 wherein a plurality of strandsof filamentary material comprising a tape are wound around theperipheral surfaces of said grinding wheels.
 4. A method as in claim 1further comprising the step of severing the strands of filamentarymaterial at the junction between said wheels after said resin is curedwhereby each wheel is reinforced by a plurality of strands offilamentary material each wrapped around portions of the periphery ofsaid wheel.
 5. A method as in claim 1 wherein the strand is saturatedwith an adhesive incorporating a resin that cures at an elevatedtemperature whereby sufficient curing time is permitted for the tensionin the turns of the wound strand to be equalized and thereby permittinguniform transfer of the loads between the strand and the peripheralsurfaces of said grinding wheels.
 6. A method as in claim 1 wherein thestrands are wound so that over 90* and less than 360* of the peripheralsurface of each wheel is traversed by the strand before crossing over tothe other wheel whereby the strand crosses from one wheel to the otherat successive positions around the periphery of the grinding faces.
 7. Amethod as in claim 6 wherein said strands are wound over approximately240* of the peripheral surface of each wheel.
 8. Apparatus forreinforcing cup-type grinding wheels having annular peripheral surfacestapering from grinding faces, said apparatus comprising: an arbor formounting a pair of wheels with their grinding faces opposing oneanother; means for yieldably urging said wheels away from one anotherwith a substantial force; means for adjustably limiting the displacementof said wheels away from one another, said adjustable displacementlimiting means positioning said wheels in a first position wherein theperipheral surfaces of said wheels are wound with a number of turns ofat least one strand of filamentary material, a portion of each turnbeing on one wheel and the remaining portion being on the other wheel,and said adjustable displacement limiting means being released to permitthe yieldable urging means to displace said wheels away from one anotherwhereby the turns of the wound strand are held in tension.
 9. Apparatusas in claim 8 further comprising: means for rotating said arbor; meansfor feeding filamentary material onto said wheels as said arbor rotates,said feed means being axially displaceable in response to rotation ofsaid arbor rotating means to feed the strand onto a portion of theperiphery of one wheel and the remaining portion on the adjacent wheelfor each turn of the arbor.
 10. Apparatus as in claim 9 wherein saidfeed means feeds the strand onto over 90* and less than 360* of theperipheral surface of each grinding wheel before feeding the strand ontothe adjacent wheel.